TSLA Premarket Mean Reversion — Backtest
Strategy 1098 · TSLA · premarket 04:00–09:30 ET · Jan 1, 2025 – Oct 21, 2026 · $10,000 per trade · paper account PA39MXU6BZPA
$2,743
Net P&L, after spread
991
Trades
54%
Winning trades
$1,789
2026 out of sample
Cumulative P&L
Daily cumulative net P&L. The dashed line marks Jan 1, 2026: parameters were chosen on data to its left only.
Rules
- Signal: z = (close − 20-bar SMA) / 20-bar standard deviation on 1-minute bars.
- Entry: Buy when z < −3; sell short when z > +3. $10,000 of TSLA, limit at the ask (buy) or bid (sell), extended hours. One position at a time.
- Exit: z back through 0, or price 2.0% against the entry. No entries from 09:15; flatten from 09:25 ET.
- Fills in the backtest: the open of the minute after the signal, plus half the bid-ask spread measured from real quotes (table below).
In sample vs out of sample
| Period | Trades | Win rate | Avg / trade | Net P&L | Max drawdown |
|---|---|---|---|---|---|
| 2025 (in sample) | 559 | 53% | 1.7 bp | $954 | $1,902 |
| 2026 YTD (out of sample) | 432 | 55% | 4.1 bp | $1,789 | $682 |
Same rules, every session
Each session was tuned the same way: best of 72 parameter combinations on 2025, then tested on 2026. The last column is the share of all 72 combinations that made money in 2026.
| Session (ET) | Best 2025 parameters | 2025 P&L | Trades | 2026 P&L | Trades | Grid > 0 |
|---|---|---|---|---|---|---|
| Premarket 04:00-09:30 | n=20, k=3, stop 2.00%, both | $954 | 559 | $1,789 | 432 | 28% |
| Regular 09:30-16:00 | n=20, k=3, stop 0.50%, long | -$271 | 258 | -$389 | 170 | 33% |
| After hours 16:00-20:00 | n=60, k=3, stop 1.00%, long | -$561 | 165 | -$914 | 115 | 0% |
| Overnight 20:00-04:00 | n=20, k=3, stop 0.50%, long | -$2,038 | 370 | -$192 | 172 | 3% |
Risks
- Thin edge. The average trade earns a few basis points, so slippage beyond the measured spread erodes it fast. Live limit orders can miss or fill worse than the backtest assumes.
- Selection. Treat this one with the most caution: only 8% of the 72 parameter combinations tested made money in 2025 and 28% in 2026, so the chosen setting may be a lucky one. Its result is also concentrated: the five best days (the April 2025 tariff selloff) made about $1,900 of the $2,743 total.
- Thin markets. Premarket quotes can be wide or stale, especially before 06:00 ET.
Monthly results
| Month | Trades | Win rate | Net P&L |
|---|---|---|---|
| 2025-01 | 50.0 | 36% | -$587 |
| 2025-02 | 37.0 | 59% | -$286 |
| 2025-03 | 44.0 | 68% | $52 |
| 2025-04 | 49.0 | 67% | $1,909 |
| 2025-05 | 59.0 | 56% | $96 |
| 2025-06 | 45.0 | 47% | -$377 |
| 2025-07 | 57.0 | 47% | -$270 |
| 2025-08 | 36.0 | 36% | -$239 |
| 2025-09 | 40.0 | 35% | -$680 |
| 2025-10 | 42.0 | 50% | $19 |
| 2025-11 | 36.0 | 81% | $1,031 |
| 2025-12 | 64.0 | 58% | $287 |
| 2026-01 | 48.0 | 56% | $364 |
| 2026-02 | 34.0 | 53% | $258 |
| 2026-03 | 44.0 | 48% | -$61 |
| 2026-04 | 42.0 | 55% | -$169 |
| 2026-05 | 39.0 | 51% | -$264 |
| 2026-06 | 49.0 | 51% | $521 |
| 2026-07 | 55.0 | 64% | $849 |
| 2026-08 | 46.0 | 57% | $26 |
| 2026-09 | 42.0 | 62% | $202 |
| 2026-10 | 33.0 | 52% | $64 |
Premarket spread used (half spread, per side)
| Hour (ET) | Median half spread |
|---|---|
| 04:00-04:59 | 2.89 bp |
| 05:00-05:59 | 2.19 bp |
| 06:00-06:59 | 2.57 bp |
| 07:00-07:59 | 1.76 bp |
| 08:00-08:59 | 1.77 bp |
| 09:00-09:59 | 2.03 bp |